Tutor MathsGuru: Ask me for your burning Maths questions!

[acehkr3009]

tianzhu:

acehkr3009:

Here is another interesting questions...


The average of the 5 numbers in a list is 54. The average of the first 2 numbers is 48. What is the average of the last 3 numbers?

Really tough, need your help on this....

Thanks in advance.

Hi

5*54 ----- 270
2*48 ------96
270- 96 -- ----174
174/3 ------58

Best wishes

Many thanks.

Solution looks simple, but when I am trying it at first, brain just got stuck and freeze!

You are really fantastic!

[tianzhu]

acehkr3009:

The ratio of Apples to Pears in a fruit stall is 5 : 8. If 60% of the pears are sold, what percentage of the apples must be sold for the number of pears and apples in the stall to be the same?

Hi

You may use MD or Units Method to solve this question.

Apples: Pears ----- 5:8 -----25:40

60% of pear% sold ----- 60/100*40 ----- 24
40% of pear left ---- (40-24) ------16

Number of apples to be sold ----- (25-16) -----9
9/25*100% ---- 36 %( percentage of apples to be sold)

Best wishes

[tianzhu]

acehkr3009:

Solution looks simple, but when I am trying it at first, brain just got stuck and freeze!

Hi

The KS way.

Keep (in) Syllabus
Keep (it) Simple
Keep (it) Short

Keep Supporting your kids

Best wishes

[Yu Xuan]

Dharma:

clblinym:

[quote=\"Dharma\"]
Ratio of Area of AEB : Area of AEC : Area of ADE = 1 : 4 : 2

Area of ABC = 1/2 X AB x Perpendicular Height
Area of ADC = 1/2 x DC x Perpendicular Height

AB : DC = Area of ABC : Area of ADC = (1+4 ) : 2 = 5 : 2

Dear Dharma,
Thank you so much for your great help.
My son and I fully understand your explanation.
We really appreciate your helpfullness.

I just want to check with you if it is a typo for the sentence.
Ratio of Area of AEB : Area of AEC : Area of ADC = 1 : 4 : 2

Sorry for the typo error. Yes , it is ADC[/quote]Hi Dharma... how did you derive the ration of AEC : ADC 4 :2 pls? Thank you for your time.

[Dharma]

Yu Xuan:

Dharma:

[quote=\"clblinym\"]





Dear Dharma,
Thank you so much for your great help.
My son and I fully understand your explanation.
We really appreciate your helpfullness.

I just want to check with you if it is a typo for the sentence.
Ratio of Area of AEB : Area of AEC : Area of ADC = 1 : 4 : 2

Sorry for the typo error. Yes , it is ADC

Hi Dharma... how did you derive the ration of AEC : ADC 4 :2 pls? Thank you for your time.[/quote]Area of ABE : Area of AECD = 1: 6
Area of ABE : Area of AEC = 1: 4

So, Area of ABE : Area of AEC : Area of ACD = 1 : 4 : (6 -4 ) = 1 : 4 : 2

[Yu Xuan]

Hi Dharma… now I see it. Thank you!!

[Dharma]

Yu Xuan:

Hi Dharma... now I see it. Thank you!!

You are welcome.

[Dharma]

acehkr3009:

Hi,


Need some help on this question.

Not sure why question appear so small.

Here is the retype of the question:

If W & Y is the mid-point of AB and CD respectively, and Z & X are any points along AD and BC respectively. What is the fraction of the shaded portion ?

Thanks.

http://www.postimage.org/image.php?

Your question looks incomplete. Can u check whether triangle AWZ is also shaded?

[Kiasu Friend]

tianzhu:

trytry:

Hi, need help.

This question was given as prelim practice:

Tom was driving from his office back to his house. As he was sick, he drove 20km/h slower. As a result, he reached home 10 minutes later.The distance between his office and house is 40km. What is his usual speed?

Tia.

Hi

Try Guess and Check

40/60 ---2/3h ----- 40min
40/80 --- 1/2h -----30min

Difference -----10min -----OK

Therefore speed -----80km/h

Best wishes

Hi tianzhu,

Thank you for the elegantly simple solution based on 'guess & check' method. But in order to understand the concept involved, can you provide a method to 'derive' the answer systematically rather than 'guessing'?

Because in the pressure of the exam-hall, 'guess & check' may be difficult to come up and quite a few wrong guesses may be tried using up precious time.

I am sorry for taking your time. Thank you very much for your tireless contribution to this forum.

[tianzhu]

Kiasu Friend:

Thank you for the elegantly simple solution based on 'guess & check' method. But in order to understand the concept involved, can you provide a method to 'derive' the answer systematically rather than 'guessing'?

Because in the pressure of the exam-hall, 'guess & check' may be difficult to come up and quite a few wrong guesses may be tried using up precious time.

Hi

Guess and Check is one of the problem solving strategies in the Primary Maths syllabus. It may be less efficient as compared to other methods, but it can help one much especially when one can’t crack a problem despite repeated trying with other strategies.

When you are in a desperate situation, with a bit of luck and some educated guesses, it may help you to secure some marks.

In this case, you need to have some number sense. What is the average speed of a car? In the exam, present your solution in a tabulated list and make at least three guesses. Even if are so lucky to get the right answer with the first guess, also try to show your answer in a systematic way so as to get the marks.

If you see a GC solution from me, it means it’s my last resort to secure some marks in an exam.At this moment, I can’t think of any other solution other than forming equations.

Best wishes